it's as if an earthquake has hit the vatican. the lights are still on, the buildings are still standing, but people here rocked by the surprise resignation of benedict xvi. it began as a routine vatican ceremony, but the pope's announcement in latin was anything but routine. "i have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the papal ministry." with that, for the first time in 600 years, a pope is resigning. benedict xvi was already old, 78, when he became pope. that was 2005. here he is almost eight years later, clearly frail and feeble. his older brother, father georg ratzinger, said today benedict is having trouble walking and had been advised by his doctors to stop traveling overseas. benedict will relinquish his papacy on february 28th. >> today's decision by benedict xvi came as a huge surprise to me, and, i think, to everyone in rome and everyone in the vatican. >> reporter: as a cardinal, joseph ratzinger was known as john paul ii's enforcer of religio